panzerman200
NAXJA Forum User
- Location
- Montana
Evening all. I have a 1998 4WD, XJ, AW4, 4.0, NP231 that's developed that famed piston slap. It has about 100k on it; perfect shape other than a few small quirks. It also has a little bit of valve train noise (sowing machine.)
I've determined that the #5 or #6 Cylinder seems to be the culprit for most of the noise. I have checked and tightened flex plate bolts just to be sure.
I'm going to tear into it this weekend and replace the lifters, oil pump (just because I'm in there), and piston(s). I've ordered all the parts other than the pistons.
My questions are as follows:
1. Should I replace all pistons since I'm in there? My fear is that since most of them are "broke in" and there's only one or two causing problems, that I may just create a problem where there is not one.
2. Can someone recommend a brand of piston? I will have limited time to work on this so quick shipping and quality are key here. I can pick up one for 40 bucks down the road at the parts shop, or 6 online for three times that.
3. Do pistons usually come with new wrist pins to press in? I'll need to hit the local shop for having them properly fitted, of course.
4. As for size of pistons... How common is it to have oversize from stock? The markings for the size are on top, correct? If there's a good chance of having stock pistons then I'd like to order them now and take a chance.
5. If the crosshatch pattern is still there and there is no ring worn into the top of the cylinder wall, can I just drop in the new piston/rings without reaming/honing?
6. Is it worth throwing new rods in? I've heard mixed reviews about that.
7. Is there anything else I can do while I'm in there that people would suggest? I've got a new exhaust manifold already that's going on. I will give everything a good cleaning and use Fel-Pro for everything. Obviously assembly lube on all metal to metal surfaces and Vaseline to prime the oil pump.
8. There's many posts about just dropping new pistons in with minimal honing and it running fine, and other posts about the absolute "Must Need" to measure the cylinder for correct fit and ordering .10 over pistons. Like I said, time is a factor here once I get it apart, so removing the block and having machine work isn't an option; Are there any thoughts about the reliability of just putting the same size piston in as before? My biggest fear is putting 6 new pistons in is just 6x the chance of messing it up if 5 of the six are fine.
Thanks so much for any tips and advice for all this.
Cheers
I've determined that the #5 or #6 Cylinder seems to be the culprit for most of the noise. I have checked and tightened flex plate bolts just to be sure.
I'm going to tear into it this weekend and replace the lifters, oil pump (just because I'm in there), and piston(s). I've ordered all the parts other than the pistons.
My questions are as follows:
1. Should I replace all pistons since I'm in there? My fear is that since most of them are "broke in" and there's only one or two causing problems, that I may just create a problem where there is not one.
2. Can someone recommend a brand of piston? I will have limited time to work on this so quick shipping and quality are key here. I can pick up one for 40 bucks down the road at the parts shop, or 6 online for three times that.
3. Do pistons usually come with new wrist pins to press in? I'll need to hit the local shop for having them properly fitted, of course.
4. As for size of pistons... How common is it to have oversize from stock? The markings for the size are on top, correct? If there's a good chance of having stock pistons then I'd like to order them now and take a chance.
5. If the crosshatch pattern is still there and there is no ring worn into the top of the cylinder wall, can I just drop in the new piston/rings without reaming/honing?
6. Is it worth throwing new rods in? I've heard mixed reviews about that.
7. Is there anything else I can do while I'm in there that people would suggest? I've got a new exhaust manifold already that's going on. I will give everything a good cleaning and use Fel-Pro for everything. Obviously assembly lube on all metal to metal surfaces and Vaseline to prime the oil pump.
8. There's many posts about just dropping new pistons in with minimal honing and it running fine, and other posts about the absolute "Must Need" to measure the cylinder for correct fit and ordering .10 over pistons. Like I said, time is a factor here once I get it apart, so removing the block and having machine work isn't an option; Are there any thoughts about the reliability of just putting the same size piston in as before? My biggest fear is putting 6 new pistons in is just 6x the chance of messing it up if 5 of the six are fine.
Thanks so much for any tips and advice for all this.
Cheers